Thanks for the comlpiment. I would also agree with you that low battery
could have been a big part of the problem. I know cars ran better when
the coil was connected correctly, but I don't remember that fault ever
being a night and day kinda difference in the way a car ran. From 1970
thru 1974, I worked in the trade on mostly MG, Triumph and Healeys, so I
saw lots of problems with them and I'd like to think I put a smile on
lots of owners faces. The last couple of those years my time was split
from my trade to finishing my degree and I retired from the auto
business when I collected my diploma. But then I was able to enjoy my
own toys and my first Elan moved into my garage in Sept '74, so I've
been at it a fair while.

While Roger is correct that the tach is polarity sensitive (as is the
radio and the coil) and may be damaged by reverse current, this does not
mean these components must be swapped out to reverse polarity. The
polarity of their connections must merely be reversed.

Of course, this is made difficult by the practice of using the case to
carry the ground voltage to the unit and the need to isolate the case
from the metal components to which it is grounded. Happily, this is not
a major issue on a glassfiber car as it is on a steel one.

I'm still puzzling over the ability of a DC motor to behave like an AC
motor. I'll take your word for it, but it ain't the natural behavior.
They must have felt that the extra cost of current-sensing logic in the
starter was worth being able to use the same starter regardless of
polarity.

The heater fan motor may be an AC unit or current-sensing as well. But
if you have electric radiator fans, they are usually DC and must have
the connections reversed to run in the right direction. This is a
common fault with the Europa cooling fans, some of which are reputed to
have come from the factory fighting the natural airflow.